Mathematical analysis of bioelectrochemical systems

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Significant amount of energy and billions of pounds are spent every year in UK to treat the industrial/domestic/municipal wastewater. However, this wastewater which typically contains a lot of organic compounds can actually be used as a valuable resource in devices known as bioelectrochemical systems (BESs). BES are like any other electrochemical cell (e.g. battery) and consist of an anode, cathode and a separating membrane (optional), but the difference lies in how the electrochemical reaction is catalysed. In BES, at least one or both of the electrode reactions are catalysed with the help of microorganisms. By combining living biological systems with electrochemistry, BES makes it possible to utilize the chemical energy from wastewater and generate electricity (microbial fuel cells, MFCs), hydrogen (microbial electrolysis cells, MECs) or value-added chemicals (microbial electrosynthesis, MES). Among different BESs, a microbial electrosynthesis (MES) system in which both electrodes are biocatalysed, makes it possible to convert wastewater (fed at the bio-anode) and waste CO2 (fed at the bio-cathode) into useful multi-carbon compounds that are precursors to commodity chemicals and transportation fuels. Such MES systems are thus of particular interest in the context of both wastewater treatment as well as CO2 capture and utilization. The electrochemical reaction in MES is however non-spontaneous and requires external energy. Renewable energy sources (solar, wind) can be used to supply the required power. Thus MES also offers a novel way to store the renewable electrical energy in the chemical bonds of organic compounds that can be stored and transported more easily. MES system performance depends on a number of biological, physical-chemical and electrochemical parameters. Following the first experimental demonstration in 2009-2010, a variety of studies have been conducted to investigate the effect of operational parameters on MES performance. These investigations have helped in improving the product yields however further improvements in performance require a deeper understanding of the mechanisms governing the process.Past research on MES has extensively focused on experimental studies, while mathematical modelling has remain neglected. The development of mathematical models will be critical to the optimization and scaling of MES systems in future. At present, there are no mathematical models available to predict the overall performance of the MES process. In this project I propose to develop comprehensive mathematical models that can not only provide insight on the governing mechanisms of MES but also on how MES systems will affect the environment. Such numerical models will compliment experiments and help to develop this technology towards commercialisation at a reduced cost and time. Development of efficient MES systems that use low-grade substrates such as wastewater and waste CO2 for chemical production provide a new technology platform for sustainable bioproduction and wastewater treatment. Such systems can help tackle environment and energy challenges in an integrated approach. Bioproduction of chemicals by consuming CO2 will also reduce the dependency on fossil fuel based carbon sources currently used in chemical industries and can assist the UK in achieving its climate targets. Thus in addition to the economic and ecological benefits, research on MES is also of major societal importance. Though the proposed research is focused on MES systems, the insight obtained from these models will also be applicable for analogous bioelectrochemical systems such as microbial fuel cells and microbial electrolysis cells. Thus the research outcomes will contribute directly towards popularizing such sustainable technologies for bioproduction of wide range of chemicals (MES, MEC) as well as generation of renewable electricity (MFC) from wastewater.